It looks like we're going to get a very crowded House series finale this May. In an impressive bit of (re-)casting, Jennifer Morrison will make a guest appearance on the final episode, "Everybody Dies."

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As first reported by TVLine, Jennifer Morrison will briefly reprise her role as Dr. Alison Cameron in the House series finale. This marks the first return of Morrison since season 6, when Cameron briefly returned in the episode, "Lockdown," to finalize her divorce from and sleep with Chase.

The casting comes as a slight surprise, due to both the character's long absence and Jennifer Morrison's current starring role on ABC's Once Upon a Time. As it is, Jennifer Morrison is the fourth former House regular set to return in the series finale. Olivia Wilde (Thirteen), Amber Tamblyn (Masters) and Kal Penn (Kutner) were all previously announced as guest stars.

This latest casting only adds more confusion to speculation about the ending of House. The title, "Everybody Dies," sounds seriously ominous -- especially when combined with the recent news of Wilson's cancer. Add in the fact that one of the returning characters -- Kal Penn's Kutner -- is already dead, and we may be looking at a fairly weird House series finale.

Will any other House regulars return for the end? Lisa Edelstein, who played Dr. Cuddy through season 7 seems a bit of a long shot. That leaves only a few recurring players like Sela Ward (Stacy Warner), Anne Dudek (Amber, aka Cutthroat Bitch), Detective Michael Tritter (David Morse), Edward Vogler (Chi McBride) and PI Lucas Douglas (Michael Weston) as possibilities for a return.

The House series finale, "Everybody Dies," will air on Monday, May 21 at 9pm on FOX (following a House retrospective at 8pm).

What do you expect from the House series finale? Do you think everyone will, in fact, die? Which House characters do you most want to see return? Leave your comments below!